Method of treating mercaptothiazoles with ammonia derivatives and product produced thereby



Patented July 25, 1944 1 METHOD OF TREATING MERCAP'I'OTHI- AZOLESWI'I'II AMMONIA DERIVATIVES AND PRODUCT PRODUCED 'I'HEBEBY' Edward L.Carr, Akron, Ohio, assignor to The 'r. Firestone Tire a Rubber Company,Akron,

.- Ohio. a corporation of Ohio No Drawing. Application December 13,1940,

. Serial No. 369,988'

8 Claims. (cacao-coat) r This invention relates to" an improved methodof treating mercaptothiazoles with ammonia derivatives and moreparticularly to an improved method of oxidizing a mixture of a2-mercaptothiazole and ammonia or mono-substituted ammonia.

This application is a continuation in part of my application Serial No.259,712, filed March 3., 1939, Patent 2,271,834. I

' An unusual class of organic chemical compounds containing bothnitrogen and sulfur may be prepared by oxidizing'a mixture of a 2-mer-.captothiazole and an appropriate ammonia derivative. The chemicalstructure of the organic chemical product of this reaction is notdefinitely known, but it is believed to be a derivative ofthiohydroxylamine (HSNHz). Thus, as an example,

the oxidation of a mixture of 2-mercaptobenzothiazole and piperidinegives rise to a white crystallin organic compound melting at 80 C.- Thissubstance is believed to be N-pentamethylene, S-Z-benzothiazylthiohydroxylamine of the following structure: I v

It has heretofore. been proposed to prepare compounds having structuressimilar to that of the above example byheating together dibenzothiazyldisulflde and av secondary amine. A white crystalline product melting at80 C. is obtained when the amine employed is piperidine. It has alsobeen proposed to prepare the same type of compound by allowing thesodium salt of 2- mercaptobenzothiazole and the N-chloro derivative of asecondary amine to interact. Thus, by the use of N-chloro piperidinethere is-also produced a white crystalline substance melting at 80 C.The reaction products obtained by each of the three above-mentionedreactions are identical. However, other structures are possiblefor thisclass of reaction products. For example, the above-mentioned reactionproduct of mercaptobenzothiazole and piperidine might possibly be aderivative of hydrazine, of the structure:

CHI-CHI Appreciation of the fact that the two above- By'means of thepresent method useful results mentioned prior methods of producing thetype of compounds discussed are rather expensive and are otherwisecommercially impracticable has led to a study of other possible methodsfor preparing said compounds, Experiments have indicated that, althoughthe oxidation of a mixture of a mercaptothiazole and an appropriateammonia derivative generally produces some of the desired compound,quantitative results have not been obtained under all conditions.Especially, it has been found that the use of one of the cheapestoxidizing agents known, chlorine, produces very low yields when ordinaryreaction conditions are employed.

After an extensive study of the oxidation reaction, it has now beenfound possible to use chlorine and yet obtain substantially quantitativeyields of the practically pure desired products. It is desirabl toemploy at least two equivalents of an alkali to each equivalentof thmercapto- .thiazole in aqueous solution and to aid in the oxidationreaction itself. The use of at leasttwo equivalents of the ammoniaderivative is preferred in order completely to preventthe formation of adithiazyl disulilde by the. oxidation of I two molecules of themercaptothiazole. By means of the new method substantially quantitativeyields of pure products may now, for the first time, be prepared veryconveniently and at low cost.

equivalents of an alkali for each equivalent of the mercaptothiazole,satisfactory resultsare also obtained with only one to twoequivalentszof alkali,

providing that a corresponding increase in the ratioof ammoniaderivative to mercaptothiazole is used. Thus, excellent yields areobtained from one equivalent of the mercaptothiazole, one

equivalent of an alkali and at least three equivalents of the ammoniaderivative. When chlorinev is replaced by-an alkali hypohalite identicalresults ar obtained with one equivalent of alkali and two equivalents ofthe ammonia derivative.-

However, the present invention contemplates the use of smaller ratios ofalkali to mercaptothiazole than the preferred ratios disclosed above.

are obtainabl so lona'as the reaction solution is maintained in adistinctly alkaline condition.

A primary object of the present invention is to provide an improvedmethod of oxidizing a mix ture of a 2-mercaptothiazole 'andan ammoniaderivative.

Another object is to provide a commercial method of oxidizing a mixtureof a z-mercapto- Although it is desirable to employ at least two thuscontemplated.

thiazole and ammonia or a mono-substituted ammonia to produce certainnitrogen and sulfur containing compounds 'at a much lower cost thanheretofore possible.

Another object i to provide a'method' of oxidizing a mixture of a.Z-mercaptothiazole and an ammonia derivative, in aqueous solution, bythe use of chlorine, bromine, iodine or'a suitable First, ammonia itselfis represented when R of the formula, W is hydrogen.

"Second, a mono-substituted ammonia of the primary amine type isrepresented by the general formula when the R is a'radical derived froma hydrocarbon, such that R is not an aryl radical.

hypohalite to produce a useful organic compound.

' A further obiect is to provide certain new organic'compoundscontaining bothnitrogen and sulfur and to Provide an emcient method forpre- Broadly stated, the present invention comprises treating an aqueousalkaline solution comprising a z-mercaptothiazole and a suitable ammoniaderivative 'with chlorine, bromine, or iodine. The invention alsocontemplates substituting for one of the above-named halogenshypochlorou's, hypobromous or hypoiodous acid, or an alkali metal oralkaline earth metal salt of one of said acids. Itis ,believed that athiohydroxylamine is formed accordingto the present method by thesimultaneous oxidation of one molecule of a mercaptothiazole (Tzrepresents a thiazyl radical in equations below) and one molecule of.ammonia (or a mono-substituted ammonia) as follows:

When a halogen such as chlorine is employed as the reagent in practicingthe present invention, the course of the reactions is believed to agreewith the following equations:

In the above equations and throughout the specification and claims "M"(or alkali metal") refers to anyone of the group including lithium,

sodium, potassium, and ammonium. The broaderv drogen, an alkyl radicalor a substituted alkyl radical.

- According to the above equations it will be seen that chlorine isthought to react first with the alkali present in the water solution toform an alkali metal hlorite. This latter compound is then'the effectiveoxidizing agent for the main reaction, indicated in the second equation.For

the purposes of the present invention, the step' outlined in the firstequationgiven above may be clearly eliminated and the method practicedby merely adding a hypochlorite to an aqueous solution comprising themercaptothiasole and the ammonia derivative. In other words, it makes nosubstantial'diiference whether the hypohalite, necessary to thereaction, is formed in the reaction solution or is preformed and thenadded thereto. The choice of oxidizing. reagent from the group mentionedabove is dependent entirely on considerations of convenience or cost.

Ammonia derivatives contemplated as operable in the present methodinclude, generally, compounds of .the formula, m, in which R is hydrogenor, in general terms, a primary alkyl radical. Two types of ammoniaderivatives ar Examples of the type of mono-substituted ammoniaderivatives contemplated by, the present invention are the followingprimary alkyl amines and substituted alkyl primary amines: methyl amine,ethyl amine, propyl amines, butyl amines,

.amyl amines, hexyl amines, cyclohexylamine,

benzyl amine, and such poly-aminesas ethylene dlamine. A radical such asthe cyclohexyl is herein considered to be a polymethylene substitutedalkyl radical.

An ammonia derivative containing less than ten carbon atoms is preferredfor solubility reasons, but the invention is not limited thereto.

The following examples are given as illustrative of the invention, butnot in limitation thereof.

Ewanmle 1 hexylamine in a total volume of 48 liters. The

molecular ratio of these reagents is: 1 mercaptobenzothiazole to 2.5NaOI-I to 2.5 RNI-Iz. This ratio of reactants represents an excess ofboth alkali and amine over the amounts required by the stoichiometricequation:

Excess of amine is employed in order to favor captobehzothiazole withthe amine rather than with itself to form dibenzothiazyl disulflde.After the completion of the reaction the unused amine may be readilyrecovered by any suitable method, such as by salting it out of thesolution. heels of alkali is employed to facilitate absorption ofchlorine toward the end of the reaction.

The reaction mixture, initially at 14 0., was contained in an iron drumwhich was fitted with eight glass nozzles extending almost to the bottomof the solution. The depth of the solution I was 30 cm. a

The reaction was carried out'as follows: Into the well stirred solutionwas passed by means of the nozzles amixture of chlorine and air at therate of 240 grams of chlorin per hour for three hours. The productprecipitated concurrently with the introductionof chlorine. After threehours the solution was depleted of mercaptob'enzothiazole, as shownbyacidifying a filtered sampleof the solution.

The crystalline product, believed to be N- cyclohexyl, S-2-ben'zothiazylthiohydroxyiamine of the structure ens-CH:- 8

was collected, washed with water and dried. Without further purificationit had a melting range of 93-99 C. The yield was practicallyquantitative on the basis of the mercaptobenzothiazole. A 7.5 per centexcess of chlorine was passed into the solution. During the course ofthe reaction the temperature gradually rose to arc. The chlorine-airmixture consisted of approximately 1 part of chlorine to from to partsof air.

Although the concentration of cyclohexylamine may vary greatly withoutsubstantially diminish-' ing the success of the present method, it hasbeen ascertained that a range oi 30 to 100 grams of the amine per literoi the reaction solution, in this instance, favors the production of apurer product and a higher yield than is otherwise obtainable.-

Example 2 1 The following semi-continuous procedure per-Q mits'obtaining the equivalent of several batches of product from a limitedvolume of solution. ,In.

the vessel suited'to the batch preparation. The I modification inprocedure consists essentially in renewing the reactants as the reactionproceeds until either the volume of solution becomes too large for thereaction vessel or the concentration 0! the halide salt produced by thereaction becomes sufllciently great to salt out the amine reactant. Inthe specific procedure described in this example, a quantity of thedesired reaction product equal to that produced in nine separate batchpreparations is obtained with only a onefold increase in the volume ofthe reaction mix- A starting reaction mixture. (a unit batch) isprepared exactly as in Example 1 in a similar'iron drum. The mixture iscooled externally with tap water to 14-19 C. in order to prevent theheat of reaction from warming the mixture to a temperature above 30 C.The reaction mixture is stirred rapidly, and a mixture of chlorine andair containing approximately one volume of chlorine to ten volumes ofair is passed thereinto through glass nozzles as in Example 1. The rateof flow of chlorine is adjusted to 9-11 ounces After the chlorine hasbeen introduced for an hour, during which time the conversion of thereactants of the initial batch to the desired product is approximatelyone-third completed, additional Z-mercaptobenzothiazole,cyclohexylamine, and sodium hydroxide. are introduced into the reactionmixture. 1 1 o The additional Z-mercaptobenzothiazole and sodiumhydroxide are introduced in the form 0! an aqueous reactant solution percent in 2'- mercaptobenzothiazole and 15 per cent in sodium aqueoussolution to the mixture; in this event, the

assess! v a 3 an equivalent rate, or 867 cubic centimeters per hour. Theintroduction oichlorine is maintained at the rate of 0-11 ounces perhounwhich is 7.5 per cent higher than the rate oi addition of the otherreactants, in order to allow for loss oi chlorine by escape from thereaction mixture.

The process is continued until a quantity oi 2- mercaptobenaothiazoleequal to eight 1600 gram batches: (together with sodium hydroxide and'cyclohexyl'amine as above indicated) have been added to the originalreaction mixture, totaling 0. quantity of mercaptobenzothiazole usedequal to nine 1600 gram batches or 14,400 grams. The addition oireactants other than chlorine is then stopped, but' the addition ofchlorine is continued uhtil the reaction mixture is' depleted of themercaptothiazole, as is apparent on acidifying a lilamine.

The semi-continuous procedure may obviously be slightly modified as toconcentrations and proportions of reactants. For instance, satisfactoryresults are obtained with the use of only two moles of alkali per moleof mercaptothiazole in the added reactant solution. Other2-mercaptothiazoles and'ammonia derivatives may be substituted for thecorresponding'ieactants in this example. .41- ternatively, chlorine maybe substituted by an alkali hypochlorite, the latter being introduced inabove-described aqueous reactant. solution containing one and one-halfmoles oi sodium hydroxide may be conveniently replaced by an equivalentsodium hypochlorite solution and the latter added separately to themixture, but concurrently with the mercaptothiazole salt solution.Example 3 I there was slowly added with stirring a saturated hydroxide,which composition represents a ratio v of one mole of themercaptothiazole to two and one-half moles of the alkali. This solutionis prepared by mixing'equivalent quantities of the mercaptothiazole andsodium hydroxide in onehalf the total amount of water required, to forma solution of the sodium salt of 2-mercaptobenzothiazole. A solution ofone and one-half equivalents of sodium hydroxide in the remainingonehalt of the total amount of water required is then mixed with thesolution of the sodium salt to form a ilnal reactant solution of theabove composition. The specific gravity of this solution at 25 C. isapproximately 1.23. This reactant solution is then added to the reactionmixture at the rate oi approximately 1730 cubic centimeters per hour or532 grams of the mercaptothiazole and 319 grams 01' sodium hydroxide perhour. Cyclohexylamine is concurrently added to the reaction mixture. at

aqueous solution of bromine. In the ensuin reaction the productprecipitated as white crystals 1 which, after being washed with waterand dried,

had a melting point of -101 C.

- Example 4 A solution was. prepared'containing 10 grams ofmercaptobenzothiazole, 4.8 grams of sodium hydroxide, and 17.8 grams ofcyclohexylamine in a volume of 250 cc. To this solution there were addedwith stirring 200 cc. of an aqueous potassium iodide solution containing15.3 grams of To 250 cc. of an aqueous solution-containing 20 grams ofmercaptobenzothiazole, 9.6 grams of sodium hydroxide and 48 grams ofcyclohexylamine there was added with stirring a saturated aqueoussolution of chlorine until the reaction mixture was depleted ofmercaptobenzothiazole.

The white crystalline product was removed from the solution, filteredand dried. Melting point 93 C. The yield was practically quantitative. 1

,point 115 C.

Example 10.

An aqueous solution of sodium hypochlorite wasintroduced with stirringinto 300 cc. of an aqueous solution containing 12.4 grams of the sodiumsalt of mercaptobennothianole and 24 grams of cyclohexylamine. Whitecrystals pre-' cipitated, which, alter being washed with water anddried, melted at 98-99 C.

Example 7 pared containing 10 grams oi. mercaptobenaothiazola, 4.8 gramsof sodium hydroxide and 19 grams of benzylamine- Chlorine gas dilutedwith air was passedinto thestirredsolutionuntilthe mercaptobenzothiazolewas depleted. The white crystallin product precipitated in practicallyquantitative yield. Melting point 115' C. The

."product is believed to be N-bensyl, S-2-benaothiasyi thiohydroxylamineoi the structure 7 The above reaction, product was proved to beidentical with the reaction product formed byheating a mixture ofdibenzothiazyl disuliide and benzylamine.

' Emmple 8 To 100 cc. of a stirred solution containing 10 grams ofmercaptobenzothiasole, 2.4 grams-of sodium hydroxide and grams ofethylene diamine there was slowly added with stirring a '5 per centsolution of sodium hypochiorite. The

' 10 An aqueous solution 01' 300 cc. volume was preproduct precipitatedas white crystals of melting E's-ample 9 v (I C8NKCsHn s 2 I Example 10A solution was prepared containing 10 grams of mercaptobenzothiazole,2.4 grams'o! sodium hydroxide and excess concentrated ammonia in avolume of 100 cc. To this solution there was added with stirring a 10per cent solution of sodium hypochlorite until the reaction mixture wasdepleted of mercaptobenzothiasole. The product was obtained in highyield as a white precipitate.

which, after being washed with water and dried,

melted at 125 C. The compound is believed to be S-2-benzothiazylthiohydroxylamine of the structure 1 Example An aqueous solution wasprepared containing. 10 grams ofmercaptobensothiasole, 4.8 grams ofsodium hydroxide and 17.5 grams of mixed monobutylaminesin a; volume of250 cc. To this solution there was addedwith stirring 200 cc. 0! anaqueous potassium iodide solution containing 15.3 grams oi i'ree iodine.The product, an amber-colored oil,- settled to the bottom. The oil wasfiltered (in ether solution) and thendried in avacuum.The-oilpartiallycrystallised'toa thickpaste.Theyieldwas13.6gramsoril5per cent of the theoretical. The product isbelieved tobeamixtureoicompoimdsoithestruc'turc Y Y "(I FQM In additionto the mercaptothiasoles-disclosed in the above examples, any othermercaptothiazole having the grouping may be employed, examples being2-mercapto Y 4-methyithiazole. 2-mercapto-4-phenyl-thiaaole and aromaticm'ercaptothiasoles, such as 2-mercapto bensothiaaole,2-mercapto-4-phenyl-bensothiasole, 2-mercapto-6-phenyi benaothiasoie,2-mercapto-naphthothiasole and homologues or the various ringsubstitution products or these substances. As typical ring substituentsthere may be mentioned nitro, halogen, hydroxyl and a xyl m ss-Theoxidisingreagentmaybeemployedina pure form or diluted with an inertmaterial, such as water or air. In the appended claims it is to beunderstood that a reagent comprisingone of the oxidising substancescomprises such substance in the chemical condition indicated and not ina state of chemical combination. This,

. "a reagent comprising chlorine" means a reagent comprising chemicallyuncombined chlorine.

-earthmetaisaltstliereofa Modification may be' resorted to, and chanicalequivalents may be empl yed. without departing from the spirit of theinvention or the scope of the appendedclaims. Whatisclaimedis: 1.Theprocesswhichccmprisesoxidisingwith asubstanceselcctedfromthesmuporhynohalous acids and alkali metal and alkaline lent ofl-merca mediumcomprking at leastone equivalent of an alkali, the temperature or saidaqueous medium beingmaintainedbelowilo'cr 4 2. The process whichcomprises treating an aqueous solution initially comprising oneequivalent or 2-mercaptobensothiasole. at least two equivalents oi,analkali metal'hydroxide and at least 2.5 equivalents oi cyclohcxylaminewith a reagent comprlsing-elmnental chlorine, the concentration of saidcyclohexylamine being main- ,tainedintherangeotwtoloogramsperliterandthetemperature oi the solution being maintained below 30 C.

3. The process which comprises treating an aqueous solution initiallycomprising one equivalent oi 2-mercaptobensothiazoie, at least twoequivalents of an alkali metal liydroxide and at least 2.5 equivalentso! cyclohexylamine with a reagent comprising elemental chlorine, theconcentration of said cyclohexylamine being maintained in the range of30 t 100 grams per liter and the temperature oi'the solution beingmaintained below 30 C.,' and gradually adding to the solution furtherquantities of Z-mercaptobenzothiazole, cyclohexylamine, and sodiumhydroxide substantially in the proportion of 1 mole: at least 1 mole: atleast 2' moles, respectively, while further treating the solution withthe reagent comprising elemental chlorine.

4. The process which comprises oxidizing with a substance selected fromthe group consisting of hypohalous acids and alkali metal and alkalineearth metal salts thereof, a mixture of one equivalent of 2-mercaptobenzothiazole and at least 2 equivalents of cyclohexylamine, inan aqueous medium comprising at least one equivalent of an alkali, thetemperature of said aqueous medium being maintained below 30 C.

5. The process which comprises treating an aqueous solution initiallycomprising one equivalent of 2-mercaptobenzothiazole at least oneequivalent of an alkali and at least two equivalents oi cyclohexylaminewith a reagent comprising a substance selected from the group consistlngof chlorine, bromine, iodine, hypochlorous at least 1 mole,respectively, while further treating the solution with said reagent.

6. The process which comprises treating an 7. The process whichcomprises treating an aqueous solution initially comprising oneequivalent of a Z-mercaptothiazole, at least one equivalent of an alkaliand at least two equivalentsof an ammonia derivative selected from thegroup consisting of ammonia, primary alkyl amines, primarycycle-aliphatic amines, primary aralkyl amines and primary poly-amineswith a reagent comprising a substance selected-from the group consistingof chlorine, bromine, iodine, hypochlorous acid; hypobror'nous acid,hypoiodous acid, and alkali metal and alkaline earth metal salts of saidacids, the temperature'of said solution being maintained below 30 C.,and gradually adding to the solution further quantities of said2-mercaptothiazole, said ammonia derivative, and

an alkali substantially in the proportion of 1 mole: at least 1 mole: atleast 1 mole, respectively,

while further treating the solution with said reagent.

8. The organic reaction product containing both nitrogen and sulfur madeby the process of claim 1.

L. CARR.

